Extreme pressure lubricant



Patented Nov. 25, 1952 UNITED STATES ATENT FFICE France, assignors to Esso Standard Societe Anonyme Francaise, Paris, France, a body corporate No Drawing. Application November 29, 1949, Se rial No. 130,064. In France March 3, 1949 '3 Claims.

The present invention relates to lubricants and more particularly, to a lubricating composition having superior extreme pressure properties. The invention also pertains to lubricants of the general type mentioned above, wherein materials such as phosphorus and sulfur and compounds thereof are included in the mineral oil bases to form high pressure lubricating compositions.

In many types of modern machinery, very high unit pressures occur between the adjoining parts of moving metallic surfaces. Unless such surfaces are effectively and continuously lubricated, rapid wear and early destruction occur. At the pressures which are sometimes employed, particularly when operating at high speeds or high torques and high temperatures, conditions arise under which ordinary lubricants are not capable of maintaining protective lubricating films. In such cases the lubricating films of oil are commonly supplemented or replaced by thin layers of chemical compounds which are formed on and from the metal of the cooperating machine parts. Thus, as is well known in the art, certain substances such as sulfur, chlorine, phosphorus, and the like, when added to lubricating oils and when subjected to high temperatures generated over limited areas by the pressure between moving parts, combine in some chemical manner with the metal of such parts to produce protective films of microscopic thickness which adhere tenaci-ously to the metal surfaces and prevent metal to metal contact.

Lubricants of the general character referred to above, may consist of blends of a petroleum oil with a saponifiable oil containing as extreme pressure agents, either as free elements or as chemical compounds, sulfur, chlorine, phosphorus, an the like. The added compounds are usually and preferably somewhat inactive chemically at ordinary operating temperatures, becoming more reactive with'the metal surfaces, however, when such surfaces are subjected to the high temperatures which result from the frictional heat generated by the transmission of power through a gear train.

In the past it has been necessary to compromise between extreme pressure additives which, on the one hand, are effective when needed to provide the. type of protecting filmmentioned above, but are objectionably corrosive over a period of time to metal such as copper and steel and those which, on theother hand, are non-corrosive, but are only moderately effective as extreme pressure agents.

Presumably, the microscopically thin protective films which are formed on metal surfaces in the manner referred to above, consist of metal sulfides, chlorides, phosphides, and the like. Thus, when sulfur, chlorine, phosphorus, and like materials are used on steel gears (such as, for example, hypoid gears in automobile driving axles) where unit pressures are very high at times, iron sulfides, chlorides, phosphides, and the like are formed. Analogous compounds are formed with other metals.

Numerous compounds have been used in the past for the purposes described above. Among them are inorganic materials such as the phosphorus sulfides, for example, Pisa, elemental phosphorus, arsenic, selenium, lead compounds, oxides of phosphorus, various chlorides, and so forth. It is well known, for example, that phosphorous sulfides may be dissolved in and/or reacted with various fatty bodies such as fatty oils, fatty acids, sulfurized fatty oils, halogenated hydrocarbons, and the like, to impart E. P. characteristics thereto. Such compositions may then be used directly asv extreme pressure lubricants, or, and more commonly, they are supplied as concentrated additives for use in small quantities in mineral oil base lubricants.

It is also known that organic phosphates, for example, tricresyl phosphate, may be used in fatty oils or acids, or in mineral oil or mixtures thereof, either with or without other additives, to impart certain desirable characteristics to lubricants. In particular, tricresyl phosphate has been found to have. certain merit as an antioxidant and as an oiliness agent.

It has now been found that a superior, extreme pressure lubricating composition may be made by incorporating into a lubricating oil that contains about 1% to 20% of a chlorinated compound and about 0.5% to 5% of a phosphorized compound, a small amount of an oil, usually about 1% to 25% containing from 13 to 25% sulfur, which exists in the form of high molecularalkylthiophenes, said percentage being by weight based on the weight of the total composition. v

The most effective sulfur compounds for use in the present invention are the heavy fractions, that is, those havingboiling points above 200 C., recovered from the distillation products of bituminous oil shales. Fractions having a boiling point below 200 C. may be used, but are generally less efiective. These sulfur bearing products consist principally of alkylthiophenes of high molecular weight. A description of the alkylthiophenes has been given in a paper by Marius Picon, presented by Paul Lepeau at the French Academy of Sciences, reported in Comptes Rendus v. 277, p. 1381. The sulfur-bearing products have a sulfur content ranging from 13% to 25% according to the fraction used. They are substantially inert when tested according to the copper strip test.

As was stated above, the preferred embodiment of this invention contemplates incorporating with the thiophenic oils, chlorinated products and phosphorized compounds to give the best results. The chlorinated products referred to may be hydrocarbons of a paraflinic cycloparaffinic or alkyl aromatic nature such as petroleum, petroleum gas oils, kerosenes, parafiins, paraffinic oils, Fischer Synthesis products, waxes, and the like, which are chlorinated to an extent of from 5 to 50% by any of the various methods known to the art. The phosphorized compounds are exemplified by tricresyl phosphate, triphenyl phosphate and trixylyl phosphate, with tricresyl phosphate being the preferred.

Another embodiment of this invention consists in utilizing as the extreme pressure agent, the sulfur-rich oils after they have been chlorinated. This chlorination may be eifected by gaseous chlorine in the presence or the absence of a solvent which does not participate in the reaction, such as carbon tetrachloride. It may also be effected in a diluent which participates in the reaction, this diluent being chosen from among the hydrocarbons cited above.

Another embodiment of this invention consists in condensing the sulfur-rich oils, the thiophenic oils described above, with a chlorinated hydrocarbon. This condensation may be eifected with the catalyst of the Friedel-Crafts type, such as aluminum chloride, boron fluoride, zinc chloride, mercuric chloride, and so forth. For this purpose can be used the above-mentioned chlorinated hydrocarbons or even chlorinated short chain hydrocarbons.

The present invention will be more clearly explained by an examination of the following examples, it being understood, of course, that these examples are given by way of illustration only, and are not to be construed as limiting the invention.

All of the tests given in the examples were made on the Faville-Levally machine, which is designed for testing lubricating oils under elevated pressures at uniform conditions. 50 grams of the oil is used in each test run on the Faville- Levally machine. At the start of the test, a three-minute running period is made with a load of 500 lbs. The load is then increased by 250 lbs. at the start of each minute. Readings are made of the couple as a function of the load, the wear of the rubbing pieces and the condition of the shaft after the test. A complete description of the machine and its method of operation, may be found in the Journal of the Institute of Petroleum, vol. 32, No. 268 of April 1946.

EXAMPLE I To a highly refined mineral oil there was added of a chlorinated gas oil having a chlorine content of 40%, and 1% of tricresyl phosphate. To this base was added fractions of a natural sulfur-bearing oil in quantities such as to pro vide a constant total sulfur content of 0.3%. The sulfur-bearing oil was obtained by distilling bituminous oil shale and fractionating the resulting product into the various cuts as defined in the table. The oil blends of these various cuts were tested in the Faville-Levally machine, and

Couple at 4,500 lb.

Composition 1 nd (p. s. 1.)

1.75 (audible seizure). 1.72 (audible seizure).

Base oil 1 Base oil +light fraction (b. below 200 0.).

Base oil +i'raction (ZOO-250 0.)... 1.63 (audible seizure). Base oil +iraction (250300 C.) 1.28. Base oil +iraction (b. above 300 C.) 0.92.

1 Base oil: Highly refined mineral oil contcining10% 01a chlorinated gas oil with a 40% chlorine content and 1% of tricrcsylphosphate.

An examination of the data reported in Table I above, will show that the light fractions of the distillation product do not give much improvement. The addition of the fraction falling between 200 and 250 C. slightly decreased the couple but did not show any appreciable decrease in the audible or grinding noises accompanying the test.

It will also be seen by examination of the table, that the fraction of the distillation product boiling between 250 and 300 0., produces a substantial reduction of the couple.

EXAMPLE II To a base mixture composed of light mineral oil and containing 10% of a chlorinated gas oil having a chlorine content of 40% and 1% of tricresyl phosphate, were added different quantities of thiophenic oil, the fraction boiling between 250 to 300 C., being utilized. These various oil blends were tested in the Faville-Levally test machine, results being given in Table II below.

Table II 1 Base oil: A light mineral oil containing 10% of a chlorinated gas oil having a chlorine content of 40% and 1% of tricresylphosphate.

An examination of the data reported in Table II will show a substantial decrease of the couple for loads in excess of 2500 lbs. after addition of the quantity of thiophenic oil up to about 3.5%. For percentages of the thiophenic oil higher than 3.5% the couple remains substantially constant at loads ranging from 2500 to 4500 lbs. In every instance, the wear on the pieces was appreciably reduced, and the surface condition of the shaft after the test was much improved by the addition of the thiophenic oil.

EXAMIPLE III A lubricant was compounded by adding to a thiophenic oil fraction boiling between 250-300 C., 10% of a chlorinated gas oil having a chlorine content of 40%, and 1% of trieresyl phosphate. The lubricant obtained gave a couple equal to 0.66 lbs. at a 4500 lb. load when tested in the Faville-Levally machine.

Table III PRESSURETESTSFAVILLE-LEVALLY MACHINE [Base oil-thipohenic' oil fraction (250-300 0.)]

Couple, p. s. i. at loadof- Com-position 3,000 lbs. 4,000 lbs. 4,500 lbs.

-Baseoil 1.12 1.37 1.47 Base oil -+7%"lhiophenic Oil 04 97 1.07

1 Base oilz' A-commercial spindle oil containing 10% of a chlorinated gas oil having a chlorine content of 40% and 1% of triorcsylphosphate.

EXAMPLE V A'thiophenic oil distilling between 250-300 'C.

was treated with a stream of gaseous chlorine at;20;C. until of chlorine had been absorbed. The "black product obtained was'then treated at 50 C. with 2% of an activated earth, and then filtered. The oil obtained had a dark brown color. This chlorinated thiophenic oil was dissolved in afluid mineral oil to make a 13% solution. The Faville-Levally test on this oil blend showed a couple equal to 0.88 lbs. under acharge of ,4500 lbs. The surface condition of the shaft after the test was excellent.

EXALKPLE VI A thiophenic oil fraction boiling above about 300 C. was ,dilutedwith 200% of carbon tetrachloride, and treated with a stream of gaseous chlorine at a temperature from to C. until the chlorine. content was'20%. The solvent was distilled .oif after the reaction product had been washed with water. 8% of the sulfur chlorinated .product obtained was dissolved in a mineral oil. The FavilleeLevally test of the blend showed a couple equal to 0.81 lbs. under a 4500 lb. load.

1 EXAMPLE VII 100 parts of a thiophenic oil boiling between 250 and'300 C. was mixed with200 parts of a paraffinic gas oil. The mixture was then chlorinated by treatment with gaseous chlorine atv a temperature of "about40 to about 60 C. until'the chlorine content was 30%. The product was then-dissolved in a fluid mineral oil to make a 10% solution. When tested on the Faville- Levall-ymachine. a couple equal to 0.81 lbs. under "a .4500 lb. load was obtained.

pEXAh/IPLE'VIII 100 grams-of a thiophenic oil fraction boiling between. 250 and 300 C. was mixed with 200 gramsof carbontetrachloride. Over aperiod of' one hour there was injected grams of sulfuryl chloride while. maintaining a temperature of 20C. After the injection of the sulfurylohloride, the mixture was heated for one hour under reflux. Evolution of sulfur dioxide occurred. The reaction product was washed with water, dried,-and the solvent was distilled 011. A 10% solution of this product in'a fluid-mineral oil, when "subjected to 'the Faville-Levally testing machine, showeda couple equal to 0.86 lb. under 9154500 *lb. load.

' and dried.

fur content of the extracted oilwas 2.5%,

One mole of heptachloropropane was condensed with two mols of a thiophenic oil fraction boiling between 100 and 150 C. in the presence of 0.2 mols of aluminum chloride. The upper layer was decanted from the aluminum com plex and distilled at a temperature of 160 C. The product obtained was washed with water 10% of this condensation product was dissolved in 90% of a fluid mineral oil. The resulting lubricant, when tested inthe Faville- Levally test machine under a 4500 lb. load gave a couple equal to 1.01 lbs.

EXAMPLE X A mineral oil rich in sulfur was obtained by extracting a spindle oil with phenol. The sul- To this extracted -,oil was added 10% of a-chlorinated gas oil having a chlorine content of 40%, and 1 of tricresyl phosphate. The lubricating oil thus compounded gave, under a 4500 lb. load in the Faville-Levally test machine, a couple equal to 0.86 lbs.

Another aspect of this invention contemplates a lubricating composition which consists essentially of a lubricating oil having combined therein a compound containing both sulfur and phosphorus in the active form. In the present in stance, this additive compound is made by treating a thiophenic-oil fraction as described above, so as to incorporate into it both chlorine and phosphorus. The phosphorizing compounds may be phosphorous sulfide (P487), phosphorous sesquisulfide, phosphorous pentasulfide, or other compounds obtained by the combination of sulfur and phosphorus. If it is desired, the desired chlorine content of the lubricating composition may be furnished by a chlorinated product as described above, that is, the chlorinated petroleums, chlorine gas oils, paraffins, parafiinic oils, Fischer Synthesis products, and etc. These chlorinated products may contain from 5 to 50% chlorine.

In treating the thiophenic oils with phosphorus-containing compounds, from 1 to 20% of the phosphorous sulfide may be used, preferably from 5 to 10%, and the temperatures of the treatment may be between 50 and 200 C. The thiophenic oil to be treated can be treated in the pure form or it may be admixed with a petroleum oil or a solvent.

The additive compounds contemplated in this aspect of the invention may be used in quantities such that the lubricant contains from 0.5 to 5% chlorine, 0.5 to 5% sulfur, and 0.02 to 1% phorphorus.

The following examples illustrate the invention and its utility, but are only given as examples and are not meant to limit the invention in any way.

EXAMPLE XI phosphorous-sulfide treated thiophenic oil and 60% of a gas oil chlorinated to 40% Table IV PRESSURE '1ESTS-FAVILLE-LEVALLY MACHINE [Base oil-P 8 treated thiophenic oil fraction (250-300 C.)]

Couple, in p. s. i. at

Composition 4,500 lbs. loud Rupture at 2,250 lbs. 1.27.

. 1.05. Base oil +l2.5% additive 0.97,

EXAMPLE XII The same tests as reported in the table above when prolonged at higher temperatures did not sensibly affect the results. The extreme pressure properties of the lubricant containing 12.5% of the additive as described above, were examined after having been submitted to a stability and oxidation test. The stability test consisted of heating the lubricating blend to a temperature of 93 C. for 48 hours; and the oxidation test consisted of heating the lubricant to a temperature of 149 C. for a period of 40 hours. The results of the Faville-Levally test after the stability and oxidation treatment are given in Table V below.

Table V PRESSURE TEST'FAVILLE-LEVALLY MACHINE [Base Oil+l2.5% Additive] Couple, in Treatment 1'). s. i. load of 4,500 lbs.

None After heating to 200 F. for 48 hours After heating to 300 F. for 100 hours The working of the shaft remains very good after the test and the wear scar was very small. It has been noted that none of the commercial agents studied correlatively with the product of this invention gave results on the Faville-Levally machine after the oxidation test. In other words, the commercial additives were not capable of withstanding the rigorous conditions of the oxidation and completely broke down when subjected to the Faville-Levally machine.

EXALlPLE XIII EXAMPLE XIV A 250 to 300 C. out of the thiophenic oil was chlorinated. to by a current of gaseous chlorine and was then treated with 10% phosphorous pentasulphide, finely divided, with agitation for one hour at 130 C. After decantation, the product was treated with 2% activated clay at C. The product was then filtered to separate the sludge. The filtered product was added to the oil base used in the preceding examples in quantities such that the chlorine content of the lubricant obtained was 3%. In a test on the Faville- Levally test machine, this oil blend gave a couple of 1.66 lbs. under a 4500 lb. load. The diametric wear of the shaft wa extremely small being on the order of 0.1 mm. and its condition was excellent.

In summation, this invention comprises a lubricating composition consisting essentially of a mineral base lubricating oil containing therein a mixture of three ingredients; (1) a distillation product of a bituminous oil shale, (2) a phosptorized compound, and (3) a chlorinated compound. It is within the scope of thi invention that the phosphorized and chlorinated compounds may be the same as the thiophenic oil, that is to say, the thiophenic oil fraction may be phosphorized and then chlorinated, or chlorinated, and then phosphorized. Although the additive compound has been recited as being blended in a mineral base lubricating oil, it is to be understood that this additive may be incorporated into either a natural occurring lubricating oil, or a synthetic type lubricating oil.

The additive of this invention is completely compatible with other lubricating oil additives such as, for example, viscosity index improvers, pour depressants, corrosion inhibitors, antioxidants, other extreme pressure agents, sludge dispersers and the like.

What is claimed is:

1. A lubricating composition which comprises a major proportion of a mineral lubricating oil and a minor but extreme pressure resistant proportion of a mixture consisting of from 1% to 20% of a chlorinated hydrocarbon, from 0.5% to 5.0% of a phosphorized aryl compound selected from the class consisting of tricresyl phosphate, triphenyl phosphate and trixylyl phosphate and about 1% to about 25% of an oil shale distillation product boiling above about 200 C. and containing high molecular weight alkyl thiophenes, said alkyl thiophenes containing from about 13% to about 25% sulfur, percentages given being by weight based on the weight of the total composition.

2. A lubricating composition Which comprises a major proportion of a mineral lubricating oil containing combined therein a minor but extreme pressure resistant proportion of a mixture of from about 1% to 20% of a chlorinated hydrocarbon, chlorinated to a chlorine content of from about 5% to about 50%, from 1% to 25% of an oil shale distillation product boiling above about 200 C. containing high molecular weight alkyl thiophenes containing from about 13% to 25% sulfur, and from 0.5% to 5.0% of an aryl phosphorized compound selected from the class consisting of tricresyl phosphate, triphenyl phosphate and trixylyl phosphate, percentages given being by weight based on the weight of the total composition.

3. A lubricating composition which comprises a major proportion of a mineral base lubricating oil having combined therein a mixture of from 5 to 15% of a chlorinated gas oil having a chlorine content of 40%, about 1% of tricresyl phosphate, and about 3 to about 8% of an oil shale distilla- REFERENCES CITED The following references are of record in the file of this patent:

Number 10 UNITED STATES PATENTS Name Date Shoemaker May 30, 1939 Prutton Oct. 31, 1939 Zimmer et a1 Aug. 6, 1946 Musselman July 13, 1948 Sproule Apr. 26, 1949 Cyphers et a1 Feb. 28, 1950 Reiff Mar. 28, 1950 

1. A LUBRICATING COMPOSITION WHICH COMPRISES A MAJOR PROPORTION OF A MINERAL LUBRICATING OIL AND A MINOR BUT EXTREME PRESSURE RESISTANT PROPORTION OF A MIXTURE CONSISTING OF FROM 1% TO 20% OF A CHLORINATED HYDROCARBON, FROM 0.5% TO 5.0% OF A PHOSPHORIZED ARYL COMPOUND SELECTED FROM THE CLASS CONSISTING OF TRICRESYL PHOSPHATE, TRIPHENYL PHOSPHATE AND TRIXYLYL PHOSPHATE AND ABOUT 1% TO ABOUT 25% OF AN OIL SHALE DISTILLATION PRODUCT BOILING ABOVE ABOUT 200* C. AND CONTAINING HIGH MOLECULAR WEIGHT ALKYL THIOPHENES, SAID ALKYL THIOPHENES CONTAINING FROM ABOUT 13% TO ABOUT 25% SULFUR, PERCENTAGES GIVEN BEING BY WEIGHT BASED ON THE WEIGHT OF THE TOTAL COMPOSITION. 